Local Mail Transfer Protocol (LMTP)

As of the Messaging Server 6.0 release, you can configure LMTP for delivery to the Message Store in a multi-tiered deployment.
In these scenarios, where you are using inbound relays and back-end Message
Stores, the relays become responsible for address expansion and delivery methods
such as autoreply and forwarding and also for mailing list expansion.

By design, LMTP is intended for use in multi-tier deployments.
It is not possible to use LMTP with single-system deployments. Also, the Messaging
Server’s LMTP service as implemented is not designed to work with other
LMTP servers or other LMTP clients.